There are a multitude of input devices for accepting user inputs to operate electronic machines. For example, a keyboard is a common input device based on a fixed key definition and key position. A mouse is another common input device, used as a controller of a cursor, for performing the function of a selector or a pointer. Ergonomic considerations have revealed that restrictive and repetitive finger movements may become a professional hazard, as in intensive use of the keyboard and the mouse over a long period.
A touch panel or screen has emerged as an alterative means for a user to input information. The touch panel has ergonomic advantages compared to the keyboard and the mouse. In addition, the touch panel may be an especially useful input device for mobile appliances such as a personal digital assistant (PDA). The touch panel provides relatively less restrictive finger movements compared to the keyboard and the mouse.
Currently, there are two types of relatively popular touch panels: a resistive type touch panel and a capacitive type touch panel. The resistive type touch panel may support a fine spatial resolution input, and it is good for handwriting input. The capacitive type touch panel may support proximity sensing, and it is good for touch control input. The capacitive type touch panel may be constructed with separate individual sensor electrodes with predefined functions to perform upon touch. Recently, the capacitive type touch panel may sense multiple touches and differentiate different touch characteristics, providing an ergonomic user interface that may detect finger touch movements.